A171862 Index of first occurrence of n in A181391, or 0 if n never appears.

1, 3, 5, 20, 17, 12, 10, 66, 47, 24, 148, 44, 173, 121, 30, 35, 138, 41, 63, 89, 56, 105, 324, 101, 215, 110, 257, 142, 320, 225, 471, 72, 59, 81, 183, 539, 134, 92, 263, 168, 129, 548, 52, 199, 179, 228, 98, 297, 621, 670, 357, 156, 116, 1486, 475

Offset

0,2

Links

N. J. A. Sloane and Reinhard Zumkeller, Table of n, a(n) for n = 0..10000 (terms 1..1594 from N. J. A. Sloane)

Mathematica

nmax = 100;
seq[m_] := seq[m] = Module[{b, last}, b[_] = 0; last[_] = -1; last[0] = 2; nxt = 1; Do[hist = last[nxt]; b[n] = nxt; last[nxt] = n; nxt = 0; If[hist > 0, nxt = n - hist], {n, 3, m}];
 A171862 = Array[b, m];
 a[n_] := FirstPosition[A171862, n];
 Table[a[n], {n, 0, nmax}] /. Missing["NotFound"] -> 0 // Flatten
];
seq[m = nmax];
seq[m = 2 m];
While[Print["m = ", m]; seq[m] != seq[m/2], m = 2 m; ];
seq[m] (* Jean-François Alcover, Aug 02 2018, borrowing some Maple code from N. J. A. Sloane *)

Prog

(Haskell)
import Data.List (elemIndex)
import Data.Maybe (fromJust)
a171862 n = 1 + fromJust (elemIndex n a181391_list)
-- Reinhard Zumkeller, Oct 31 2011

Crossrefs

Cf. A181391, A171863, A171864.

Sequence in context: A303937 A062577 A144743 * A231627 A261116 A295361

Adjacent sequences: A171859 A171860 A171861 * A171863 A171864 A171865

Keyword

nonn

Author

N. J. A. Sloane, Oct 17 2010

Extensions

Offset corrected by Reinhard Zumkeller, Oct 31 2011

Status

approved